On Dec 9, 10:37*pm, Darryl Ramm wrote:

I don't think the wing interior to spoiler box connection (where the
control rods enter the spoiler box) is all that airtight on most
gliders and will see ambient internal wing/fueslage pressure...

In my experience, the better racing gliders generally have pretty well-
sealed airbrake boxes. I think that it's a common practice to use a
rubber bellows to seal the push-pull tube entry. I don't use a
bellows, but my airbrake boxes are also sealed off from the wing
interior.

Thanks, Bob K.